This invention (structure and method) relates to building structure, and in particular to a novel column/beam/collar-interconnect structural organization (and related methodology) which functions to create an improved and very capable moment-resistant frame for a building. Featured in the practice of the invention is a unique, bearing-face collar-interconnect structure which joins adjacent columns and beams at nodes of intersection between them.
In the ongoing effort to improve building frame structure, and particularly to improve such structure so that it can better handle severe lateral loads, such as earthquake loads, much attention has been focused on the manner in which upright columns and horizontal beams are connected. The present invention especially addresses this issue, and in so doing, offers a number of unique and important advantages in building-frame construction, and in ultimate building-frame performance.
According to a preferred embodiment of, and manner of practicing, the present invention, the invention proposes a column-beam interconnect structural system and methodology wherein the ends of beams are joined to columns at nodes of intersection through unique collar structures that effectively circumsurround the sides and the long axes of columns to deliver, through confronting bearing faces, compressive loads which are derived from moment loads experience by the beams. In particular, the delivery through compression of moment loads carried from beams to columns involve the development in the columns of vertically offset reverse-direction compression loads which create related moments in the columns. With respect to each and every lateral load that is experienced by a building frame constructed in accordance with the invention, all lateral loads are essentially equally shared by all of the columns, and a consequence of this is that, in comparison to building frame structures built conventionally, a building frame structure constructed in accordance with this invention prevents any single column from carrying any more load than is carried by any other column. As will become apparent, this important feature of the invention, as it performs, enables a building to be constructed in such a way as to exceed minimum building code requirements in many instances, and thus open the opportunity for using a building frame in accordance with this invention in settings where conventional frame structure would not meet code requirements.
The nodal connections which result from practice of the present invention function to create what is referred to as three-dimensional, multi-axial, moment-coupling, load transfer interconnection and interaction between beams and columns.
Focusing on the specific load-delivery interaction which occurs between a given single column and a connected single beam that bears a moment load, this load is coupled compressively into the column by the associated, single, nodal collar structure at plural bearing-face regions which are angularly spaced about the column's long axis. Compressive load-transfer coupling is not constrained to just one plane of action, or to just one localized region of load delivery. Compression couplets are created to take fuller advantage of columns' load-handling capabilities.
The proposed nodal collar structures include inner components which are anchored, as by welding, to the outside surfaces of columns, and an outer collar which is made up of components that are suitably anchored, also as by welding, to the opposite ends of beams. The inner and outer collar components are preferably and desirably formed by precision casting and/or machining, and are also preferably pre-joined to columns and beams in an automated, factory-type setting, rather than out on the construction job site. Accordingly, the invented collar components lend themselves to economical, high-precision manufacture and assembly with columns and beams, which can then be delivered to a job site ready for accurate assembly.
As will become apparent from an understanding of the respective geometries proposed by the present invention for the collar components, these components play a significant role during early building-frame assembly, as well as later in the ultimate performance of a building.
At the regions of connection between beams and columns, and with respect to pairs of adjacent columns standing upright approximately correctly (vertically) in space on a job site, as beams are lowered into horizontal positions, the outer collar components that they carry at their opposite ends seat under the influence of gravity through special, angular, bearing-face geometry provided in them and in the confronting inner column components. This bearing-face geometry effectively guides and collects a lowered beam, and the associated two columns, into stabilized, gravity-locked conditions, with these now-associated beam and column elements then essentially correctly aligned and positioned in space relative to one another. Male/female cleat/socket configurations formed in and adjacent the confronting bearing-face portions of the inner and outer collar components function under the influence of gravity, during such preliminary building construction, not only to enable such gravity locking and positioning of the associated frame components, but also to establish immediate, substantial stability and moment resistance to lateral loads, even without further assembly taking place at the nodal locations of column-beam intersections.
Following preliminary frame assembly, appropriate tension bolts are preferably introduced into the collar structures, and specifically into the components of the outer collar structures, effectively to lock the inner and outer collar structures in place against separation, and to introduce available tension load-bearing constituents into the outer collar structures. Such tension load bearing plays an important role in the way that the structure of the present invention gathers and couples beam moment loads multidirectionally into columns.
Confronting faces between the inner and outer collar components function as bearing faces to deliver, or transfer, moment loads (carried in beams) directly as compression loads into the columns. In particular, these bearing faces deliver such compression loads to the columns at plural locations which are angularly displaced about the long axes of the columns (because of the axial encircling natures of the collars). Such load distribution takes substantially full advantage of the load-carrying capabilities of the columns with respect to reacting to beam moment loads.
Accordingly, a building frame structure assembled in accordance with this invention results in a remarkably stable and capable frame, wherein all lateral loads transfer via compression multiaxially, and at distributed nodes, into the columns, and are born in a substantially relatively evenly and uniformly distributed fashion throughout the entire frame structure. Such a frame structure requires no bracing or shear walls, and readily accommodates the later incorporation (into an emerging building) of both outer surface skin structure, and internal floor structure.
The nodal interconnections which exist between beams and columns according to this invention at least from one set of points of view, can be visualized as discontinuous floating connections—discontinuous in the sense that there is no uninterrupted (homogenous) metal or other material path which flows structurally from beams to columns and floating in the sense that beams and columns could, if so desired, be nondestructively disconnected for any particular purpose. Thinking about the latter consideration from yet another point of view, the connective interface that exists between a beam and a column according to this invention includes a portion which experiences no deformation during load handling, such portion being resident at the discontinuity which exists between beams and columns at the nodal interfaces.
These, and various other, features and advantages which are offered by this invention will become more fully apparent as the description that now follows is read in conjunction with the accompanying drawings.